Post- forming heads on fastener elements

Abstract

A method and apparatus of producing a fastener product having a multiplicity of fastening members with stems integrally molded with a strip-form base, along with a product and a preform product so produced. Molten resin is applied to a rotating mold roll having an outer surface for forming one side of the base, and a multiplicity of cavities extending inward from the outer surface for molding the stems. A preform product is stripped from the mold roll having a multiplicity of upstanding, preform stems extending from a side of the base. The preform product is passed through a post-forming nip between a heading roll and a backing member to form overhanging heads at the distal ends of the upstanding stems. The heading roll has a multiplicity of cavities about its periphery for forming the heads. Various means are disclosed for aligning the preform stems and the heading roll cavities. In another embodiment, a dimpled, heated heading roll is employed to post-form the stems to form fastener elements that extend in random directions.

What is claimed is:  
     
       1. A method of producing a fastener product having a strip-form base and a multiplicity of fastening elements extending from a side of the strip-form base, the method comprising the steps of: 
       applying resin to a rotating mold roll, the mold roll having an outer surface for forming one side of the base and defining a multiplicity of cavities extending inward from the outer surface, under conditions which cause the resin to fill the cavities and form said side of the strip form base on the outer surface of the mold roll;  
       stripping from the mold roll a preform product having said strip-form base and a multiplicity of upstanding, preform stems formed in the cavities of the mold roll and extending from said side of the base; and  
       registering a longitudinal position of the preform stems with a rotational position of a heading roll while passing the preform product against the heading roll to form, from resin of the stems, a head on each of the preform stems, to form said fastener elements, the heading roll defining a multiplicity of cavities about its periphery which receive the preform stems and form the heads to overhang sides of their stems in multiple directions to form mushroom fastener elements.  
     
     
       2. The method of claim  1  including molding a series of alignment features in the preform product with the mold roll, and then using the alignment features to longitudinally register the preform stems with the rotational position of the heading roll. 
     
     
       3. The method of claim  2  including, after the step of passing the preform product against the heading roll, trimming the strip-form base between the series of alignment features and the fastening elements to produce a strip-like fastener product without said alignment features. 
     
     
       4. The method of claim  2  including, after passing the preform product against the heading roll, trimming the strip-form base between the row of alignment features and the fastener elements to produce a strip-like fastener product without said alignment features. 
     
     
       5. The method of claim  1  wherein the step of registering comprises mechanically coupling a registration means on each of the mold and heading rolls to register the rotational position of the heading roll with respect to the mold roll. 
     
     
       6. The method of claim  1  wherein the step of registering comprises sensing a series of alignment features of the preform product. 
     
     
       7. The method of claim  6  wherein the alignment feature is sensed optically. 
     
     
       8. The method of claim  6  including, after passing the preform product against the heading roll, trimming the strip-form base between the series of alignment features and the fastening elements to produce a strip-like fastener product without said alignment features. 
     
     
       9. The method of claim  1  wherein the cavities of the heading roll are substantially of the shape of the formed heads. 
     
     
       10. The method of claim  9  wherein the formed, overhanging heads are of conical shape, having uppermost surfaces forming apices. 
     
     
       11. The method of claim  10  wherein the apices each define an included angle of less than about 90 degrees. 
     
     
       12. The method of claim  11  wherein the apices each define an included angle of less than about 60 degrees. 
     
     
       13. The method of claim  1  including maintaining the heading roll at an elevated temperature to soften distal ends of the stems of the preform product. 
     
     
       14. The method of claim  1  wherein the formed, overhanging heads each overhang their respective stems in elevational view by an overhang distance at least about 25 percent of the width of their respective stems. 
     
     
       15. The method of claim  14  wherein the formed, overhanging heads each overhang their respective stems in elevational view by an overhang distance at least about 50 percent of the width of their respective stems. 
     
     
       16. The method of claim  1  wherein the cavities of the mold roll comprise cylindrical holes extending inward from the surface of the mold roll. 
     
     
       17. The method of claim  1  wherein the cavities of the mold roll comprise axial slots extending between broad sides of disk-form mold plates stacked to form the mold roll. 
     
     
       18. The method of claim  1  wherein the cavities of the mold and heading rolls are adapted to form mushroom-type fastening elements with heads that overhang their stems generally equally in all directions. 
     
     
       19. The method of claim  1  wherein the cavities of the mold and heading rolls are adapted to form multi-lobal fastener elements with multiple, outwardly-projecting ridges extending along their stems, such that the stems have polygonal cross-sections, the heads having multiple, overhanging lobes corresponding to the ridges of the stems. 
     
     
       20. A method of producing a fastener product having a strip-form base and a multiplicity of fastening elements extending from a side of the strip-form base, the method comprising the steps of: 
       applying resin to a rotating mold roll, the mold roll having an outer surface for forming one side of the base and defining both a multiplicity of stem-forming cavities and a series of alignment feature-forming cavities extending inward from the outer surface, under conditions which cause the resin to fill the cavities and form said side of the strip-form base on the outer surface of the mold roll;  
       stripping from the mold roll a preform product having said strip-form base, a multiplicity of upstanding, preform stems formed in the stem-forming cavities of the mold roll and extending from said side of the base, and a row of alignment features formed in the alignment feature-forming cavities of the mold roll and extending from the base; and  
       passing the preform product against a heading roll while employing the alignment features to register a longitudinal position of the preform stems with a rotational position of the heading roll, thereby forming a head on each of the preform stems from resin of the stems, to form said fastener elements.  
     
     
       21. The method of claim  20  wherein the longitudinal position of the preform product is registered with a rotational position of the heading roll by sensing the alignment features. 
     
     
       22. The method of claim  21  wherein the alignment features are sensed optically. 
     
     
       23. The method of claim  20  wherein the heads are formed on the preform stems in heading roll cavities of substantially the shape of the formed heads. 
     
     
       24. The method of claim  23  wherein the formed, overhanging heads are of conical shape, having uppermost surfaces forming apices. 
     
     
       25. The method of claim  24  wherein the apices each define an included angle of less than about 90 degrees. 
     
     
       26. The method of claim  25  wherein the apices each define an included angle of less than about 60 degrees. 
     
     
       27. The method of claim  20  including maintaining the heading roll at an elevated temperature to soften distal ends of the stems of the preform product. 
     
     
       28. The method of claim  20  wherein the step of passing the preform product against the heading roll forms overhanging heads which overhang their respective stems in elevational view by an overhang distance at least about 25 percent of the width of their respective stems. 
     
     
       29. The method of claim  28  wherein the step of passing the preform product against the heading roll forms overhanging heads which overhang their respective stems in elevational view by an overhang distance at least about 50 percent of the width of their respective stems. 
     
     
       30. The method of claim  20  wherein the cavities of the mold roll comprise cylindrical holes extending inward from the surface of the mold roll. 
     
     
       31. The method of claim  20  wherein the cavities of the mold roll comprise axial slots extending between broad sides of disk-form mold plates stacked to form the mold roll. 
     
     
       32. A method of producing a fastener product having a strip-form base and a multiplicity of fastening elements extending from a side of the strip-form base, the method comprising the steps of: 
       applying resin to a rotating mold roll, the mold roll having an outer surface for forming one side of the base and defining a multiplicity of cavities extending inward from the outer surface, under conditions which cause the resin to fill the cavities and form said side of the strip-form base on the outer surface of the mold roll;  
       stripping from the mold roll a preform product having said strip-form base and a multiplicity of upstanding, preform stems formed in the cavities of the mold roll and extending from said side of the base, the stems arranged in spaced, parallel rows extending in the machine direction; and  
       passing the preform product against a heading roll to form, from resin of the stems, a head on each of the preform stems, to form said fastener elements, the heading roll defining a multiplicity of cavities about its periphery which receive the preform stems and form the heads to overhang sides of their stems in multiple directions, the cavities of the heading roll being arranged to randomly intercept the preform stems and to, in addition to forming the overhanging heads, bend at least some of the stems in different directions, the cavities of the heading roll having an overall depth of less than about 0.5 times the spacing between adjacent, machine direction rows of stems.  
     
     
       33. A method of producing a fastener product having a strip-form base and a multiplicity of fastening elements extending from a side of the strip-form base, the method comprising the steps of: 
       applying resin to a rotating mold roll, the mold roll having an outer surface for forming one side of the base and defining a multiplicity of cavities extending inward from the outer surface, under conditions which cause the resin to fill the cavities and form said side of the strip-form base on the outer surface of the mold roll;  
       stripping from the mold roll a preform product having said strip-form base and a multiplicity of upstanding, preform stems formed in the cavities of the mold roll and extending from said side of the base, the stems arranged in spaced, parallel rows extending in the machine direction; and  
       passing the preform product against a heading roll to form, from resin of the stems, a head on each of the preform stems, to form said fastener elements, the heading roll defining a multiplicity of cavities about its periphery which receive the preform stems and form the heads to overhang sides of their stems in multiple directions, the cavities of the heading roll being arranged to randomly intercept the preform stems and to, in addition to forming the overhanging heads, bend at least some of the stems in different directions, adjacent cavities of the heading roll being spaced at a cavity spacing distance of less than about 0.8 times the spacing between adjacent, machine direction rows of stems.  
     
     
       34. The method of claim  33  including maintaining the heading roll at an elevated temperature to soften distal ends of the stems of the preform product. 
     
     
       35. The method of claim  33  wherein the step of passing the preform product against the heading roll forms overhanging heads which overhang their respective stems in elevational view by an overhang distance at least about 25 percent of the width of their respective stems. 
     
     
       36. The method of claim  35  wherein the step of passing the preform product against the heading roll forms overhanging heads which overhang their respective stems in elevational view by an overhang distance at least about 50 percent of the width of their respective stems. 
     
     
       37. The method of claim  33  wherein the cavities of the mold roll comprise cylindrical holes extending inward from the surface of the mold roll. 
     
     
       38. The method of claim  33  wherein the cavities of the mold roll comprise axial slots extending between broad sides of disk-form mold plates stacked to form the mold roll. 
     
     
       39. The method of claim  33  wherein at least some of the preform stems are bent by the heading roll to form hook-shape fastener elements, and at least some of the preform stems are headed by the heading roll without being bent. 
     
     
       40. The method of claim  33  wherein the cavities of the heading roll have an overall depth of less than about 0.5 times the spacing between adjacent, machine direction rows of stems. 
     
     
       41. The method of claim  33  wherein the cavities of the heading roll define a cavity portion of the heading roll, the heading roll cavities extending into the heading roll from rectangular bases, the bases of the heading roll occupying at least 90 percent of the circumferential area of the heading roll along the length of the cavity portion of the heading roll.